This invention relates to a coffee maker which has a dosage signaling assembly and which includes a filter basket accommodating ground coffee as well as a water reservoir communicating with a vapor generator, particularly a flow heater and wherein the vapor generator has a discharge end from which brewing water is introduced into the filter basket.
In known coffee makers of the above-outlined type, particularly in coffee makers for household use, brewing water flows from the water reservoir (which forms part of the coffee maker) through a flow heater for heating the water to the brewing temperature. Subsequently, by means of the vapor pressure generated in the flow heater, the brewing water is guided by a rising conduit to the filter basket which is lined by a filter insert and which accommodates the ground coffee. The brewing water percolating through the ground coffee becomes the coffee beverage which runs into a coffee pot positioned underneath the filter basket. The strength of the brewed coffee beverage is determined as a function of the ratio of the metered ground coffee quantity in the filter basket to the brewing water quantity passing through the ground coffee. To brew coffee according to the desired concentration (strength), conventional water reservoirs have a transparent portion carrying a scale which marks cup quantities to guide the operating person in filling the reservoir with water corresponding to the desired quantity of coffee beverage. As a rule, dosing a ground coffee quantity which is associated with a desired beverage strength is conventionally effected by a measuring spoon whose volume is designed such that it may accommodate a ground coffee quantity which yields a cup of coffee of normal strength. The dosing with such an arrangement, however, is circumstantial because care has to be taken that the measuring spoon is accurately filled and, if required, the dosing has to be repeated several times. It is a further drawback that dosing according to such a conventional procedure is very frequently inaccurate, because often the measuring spoon is charged with too much or too little ground coffee. A desired defined change of the concentration of the coffee beverage is even more difficult to achieve because the measuring spoon has only a single determined capacity.
German Utility Model No. 297 01 818 discloses a digital coffee level indicator which makes unnecessary a measuring spoon count while the filter basket of a household coffee maker is filled with ground coffee. For this purpose a precision weight sensor is provided at a location where the filter basket is suspended. The weight sensor is coupled with a digital indicator to display the weight of ground coffee present in the filter basket. Based on such a digital display, however, the filter basket may be charged with coffee of the desired weight only if the weight/strength relationship is known to the operating person who thus may monitor the coffee weight on the digital display. Thus, the operating person needs to know for all brewing water quantities the associated ground coffee quantities of the desired strength; such information, in all likelihood, needs to be obtained from a graph. It is a further drawback of such a digital display system that it requires attention because, as the displayed value varies, there is no positive "yes" or "no" indication whether excessive or insufficient amounts of ground coffee are displayed.
European Published Patent Application 536 714 discloses an automatic metering device for ground coffee, by means of which the desired concentration of the coffee beverage is obtained automatically. The ground coffee is introduced into a filter basket in a controlled manner by a disk which has compartment-forming vanes and which is situated underneath a ground coffee container. The metering device is driven by a motor unit operated by a control circuit. The control circuit, which is not described in detail, may be programmed according to the desired strength of the coffee beverage. The motor unit then meters, on the one hand, the volume of water which, corresponding to the desired number of cups, is directed to a flow chamber and, on the other hand, rotates the disk to an extent to discharge the ground coffee into the filter basket from a determined number of compartments. This automatic metering device, however, is complicated and expensive.